crabtree



(No Model.) 4 Sheets-Sheet 1.

' J. CRABTREB.

AIR OR'GAS COMPRESSOR.

V' No. 594,524.

Patented Nov. 30, 1897.

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ATTH/VEY.

(No Model.) 4 Sheets-Sheet 2.

J. GRABTRBE.' AIR 0R GAS COMPRESSOR.

No. 594,524. Y Patented Nov. so, 1897.

ATTOH/VEY uma., wAsHmGToN D c 4 Sheets-Sheet 3.

(N0 Mod-el.)

vJ. CRABTRBE. AIR 0R GAS COMPRESSOR.

N0. 594,524. Patented NOV. 30, 1897.

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ATTORNEY.

4 Sheets-Sheet 4.

(No Model.)

J. GRABTREE. AIB. 0R GAS COMPRESSOR. No. 594,524. Patented Nov. 30,1897.

i `-NITED STATES PATENT Erica.

AIR OR GAS COMPRESSOR.

SPECIFICATION forming part of Letters Patent lvm-594,524, dated November30, 1897.

Application led April l 3 1 39 6.

To all whom it may concern:

Be itknown that I, JONAS CRABTREE, a citizen of the United States,residing in the city of` New York, inthe county, and State of New York,have invented a certain new and useful Improvement in Air or GasCompressors, of which the following is a specication.

The subject of the present invention is an improved vmachine forcompressing air, gas, or other iiuid, and is principally designed tosecure economy of working energy and the most advantageous applicationof the actuating power and attain simplicity of construction andreduction of weight in the moving and otherparts of the machine.

As will further appear, the improved compressor also embodies certainnovel details and parts which contribute to high efficiency ofoperation. Y

The accompanying drawings form a part of this speciiication andrepresent what I consider the best means of carrying out the in-Avention.

Figure I is a plan view showing my improved compressor. It also shows inoutline on its lower side an additional engine to be operated by thesubsequent expansion of the air which has been compressed. Fig. 2 is aview representing in side elevation one'form of compressor embodying myimprovements. Fig. 3 is a detail sectional view of one of thecompressing-cylinders and its trunnions, the section being taken in theplane indicated by the dotted line d h in Fig. 2. Fig. 4 is a horizontalsectional view through the inner connection with the slide-bar of onepair of heads of the rods attached to the compressing-pis ton, and Fig.5 is a detail sectional View showing on an enlarged scale theconstruction and arrangement of the supply and delivery valves of one ofthe compressing-cylinders. Fig. 6 is an enlarged detail sectional planView showing the heads of the piston-rod as of gear form. Fig. 7 is adetail view of the parts shown in Fig. 6, but represented in differentposition. Fig. 8 is a somewhat similar view, but illustratin g theemployment of elliptical heads for increasing the stroke of thecompressingpistons. Fig. 9 is a View of the guides detached.

Similar reference-numerals indicate correserin No. 587,313.. (No modemsponding parts in all the figures Where they appear.

The framework I is suitably bolted to the rear end of the steam-cylinder2, which may be of the Oorliss or other approved style. rIhe said frameis so constructed that its main parts can be adjusted for compressors ofvarying size.

3 and 4 designate the primary and 5 and 6 thesecondary,compression-cylinders, which as represented are ofsingle-acting and oscillating character and are relatively located withregard to each other and the slide-bar 7, (reciprocated by thesteam-piston,) asmost clearly shown in Fig. l. While I have shown fourof such cylinders, it will be obvious that for the purpose of securinghigh compression their number may be increased to any desired extent.

Each of the compression-cylinders is pivotally mounted in bearingscontiguous to its inner end and is provided with upper and lowervtrunnions 9 l0,each of which contains an opening 11, (seeFig. 3,)surrounded at the mouth by an annular recess 12 for the reception of asuitable packing material. The recess l2 is separated from the openingll by a rim of metal 12a. The retaining cap or plate 13 for eachtrunnion has an annular projection 14 to enter the packed recess 12 toestablish an air-tight joint with said trunnion when the plate isadjusted and bolted to the main frame, as shown in Fig. I. A cross-barl5 is bolted to the inner end of each compression-cylinder and serves asa rod-guide to avoid any undue friction between the compressing-piston16 and the cylinder and also assist in the movement of the latter.

The rods 17 of the compressing-pistons are provided at their-inner endswith cylindrical heads 18, each pair of which is so connected with thebar 7 by yoke-plates 7 5K, bolted thereto, as to permit each head toturn in its bearing and its rod to make a vibrating movement back andforth as the bar 7 reciprocates, the said heads of each pair being incontact, as illustrated in Fig. 4, so as to have a rolling motionagainst each other, thus serving to reduce friction. Where the heads areof strictly cylindrical form,blocks 19,adj ustable through the medium ofbolts 20, are employed to secure ICO a snug'bearing for the heads andtake up wear.

In the inner ends of the cylinders induction and delivery valves 2l and22 are arranged and control communication through ports or passagesextending through the trunnions, the valves 2l of each primary cylinderclosing the supply through an extended passage 23,1eadingfrom theopening in the lower trunnion, while the valve 22 of each of saidcylinders cuts off communication with an extended passage 24, leading tothe opening in the upper trunnions, both the primary and secondarycylinders having pipe connections 25 and 2G with a receiver or reservoir27, containing a cooling-coil.

Assuming that the piston of the engine is at the center of its stroke,the compressingpistons are at the limit of their inward movement, asindicated by full lines in Fig. l. The further movement of theengine-piston and slide-bar causes the pistons to be moved outward. Airis drawn in through the lower trunnions of the compression-cylinders 3and 4,-, then flows along the port or passage 23 on the under side tothe chambers 29 of the induction -valves through the openings controlledby the latter into the cylinders. In some cases communication may beestablished directly with the atmosphere through the valved end of thecylinders or through the pistons. The succeeding inward movement of thepistons in the cylinders 3 et seats the induction-val ves, compressesthe air, and forces it through the openings controlled by thedelivery-valves 22, after which it flows along the passage 2l to andthrough the upper trunnions and pipes 25 25 to the receiver, where itstemperature is reduced by the cooling-coil. The air next passes from thereservoir by way of pipes 26 2G to the secondary compressioncylinders 5G, wherein it materially assists in the completion of the stroke of thesteam-piston. The return movement of the pistons in the cylinders 5 Gexpels the air in a highlycompressed condition through the lowertrunnions of said secondary cylinders and from which it may be conveyedto any suitable point for utilization in refrigerating apparatus or anyplace to be artificially cooled. It will be comprehended that the valvesand passages in the cylinders 5 (3 are reversed relatively to those inthe cylinders 3 4. It will also be noted that the construction of theimproved compressor is such that one revolution of the crank-shaft 3lsuffices to cause two complete strokes of the compressing-pistons,thuscompensating for their comparatively short stroke, the combined effectof the four pistons being equivalent to a double-acting directaircompressor requiring much greater motive power.

The fly-wheel 32 and shaft 3l serve not only to regulate the stroke ofthe compressing-pistons, butlimit the stroke of the steam-piston,

while at the same time throwing the rods 17 beyond their centers.

The sliding bar 7, although of comparatively extended length andprovided with large wearing-surfaces, is subjected to very little sideor vertical pressure, it being properly guided by guides 32, havingintegral lugs 33, provided with bearing-plates bolted to the frame l, asshown in Fig. 2.

From so much of the description as has thus far been furnished it willbe comprehended that the energy of compression is utilized to thehighest possible extent, inasmuch as the power is applied at the apex ofthe angle formed by the piston-rods and the slide-bar 7 and transmittedby the former in a direct line to their pistons through the chan gingpositions .of their eylinders,any loss of power experienced by onepiston heilig compensated for by the coaction of the others. It willalso be seen that as the pressure in the compression-cylinders increasesthe relation of each cylinder, its piston, and rod to the line of thereciprocating bar will become more nearly a right angle, so that thesame power, as each pair of rods approaches alinement with each otherand a position at right angles with said bar, will exert increasingcompression effect, since the mutual bearing of each pair of rods attheir inner ends tends to force each other outward, thus avoiding lossof energy.v

Another important feature connected with this invention is the provisionof having the compressing-pistons commence their outward stroke at theirhighest speed, which becomes gradually reduced as compression proceedsto the limit of their inward movement. 3y this arrangement the pistonscan be adjusted to work close to the cylinder ends, thereby avoiding theusual loss of capacity from clearances. The greatest working resistanceis encountered by the steam-piston in the second quarter and until itpasses the center of its stroke, the second half of the piston movementbeingassisted by the air-pressu re in the secondary cylinders, so thatthe steam maybe cut off early and expanded to secure economy in workingthe engine.

The arrangement of the induction and delivery valves of cach of thecylinders 3 -t is shown on an enlarged scale in Fig. 5, wherein 35represents the interior of the cylinder at the cylinder-head; 36, theinlet-valve chamber; 37, the delivery-valve chamber. 'ihc inlet-valvev35) is of the winged form and carries the head 40, threaded to engagethe cap atl, which not only serves to guide the valve, but also toadjustably limit its movements and serve as a piston to effect theclosing of the valve by forming a partial vacuum as it opens. The cap 42serves as a cylinder for inducing such closing motion. The cap 4l isintroduced and adjusted through an opening in the outer casing of thevalve-chamber,

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which opening is closed by a cap 42, having a collar 43 engaging thethreads of the casingopenin g and extending within the valve-chamber toreceive and permit the cap 41 to snugly move therein.

The threaded portion of the cap 41 is of greater diameter than the innercontracted mouth of the valve-opening, so that when the induction-valveleaves its seat the free edge of the threaded portion of the capi 41will contact with the inner casing of the valvechamber and limit themovement of the valve. By varying the threaded engagement of the capwith the head the limit of contact may be adjusted and hence themovement of the valve regulated. The delivery-valve 44 is also of thewinged type, but is obviously introduced through a threaded opening inthe outer casing of its chamber, said opening being closed by a cap 45,the threaded collar 46 of which extends within the chamber 37 and snuglyreceives and admits of the play within it of the head 47 of thedelivery-valve. A small port 48 is located in the collar 46, asindicated.

When the piston moves outward in each of the'compression-cylinders,thevalve 39 opens, thus creating between the caps 41 and 42 a partialvacuum and at the same time permitting air to be drawn into thecylinder. When the piston ceases to draw air, the vacl num in connectionwith the opposition airpressure exerted on the valve tends to quicklyand positively reseat it. The delivery-valve opens as soon as theair-pressure in the cylindcr exceeds that of the chamber and receiver.Vhen the delivery-valve leaves its seat in opening, a small volume ofair under pressure is admitted through the port 4S to the space betweenthe head 47 and cap 48, the further movement of thevalve cutting offsaid port. Now whenever pressure is removed from the inside of thecylinder the confined air between the head 47 and its closing-capexpands and causes the valve to positively and quickly resume its seat.

In order to effect the two complete strokes of the compressing-pistonsheretofore referred to, it is highly important that the trunnions orbearings of each pair of opposed cylinders should be as close togetheras possible, while permitting mutual clearance of the inner corners ofsaid cylinders. The relative location of the bearings indicated in Fig.1 is sufficient to enable the rod of each compressingpiston to assume atthe limit of the enginestroke in either direction a position that willhave brought the piston to its outward movement. The bar may be providedwith recesses or be otherwise formed to present suitable clearance forthe cylinder corners and permit their working close together.

Modifications may be made without departing from the principle orsacrificing the advantages of the invention. Parts of the invention canbe used without the whole. Gears may be cut or otherwise produced on theheads of the compressing piston-rods, aiding the stout inclosing partsor housing to keep the heads in their proper working positionsrelatively to each other. Such arrangement is shown in Figs. 6 and 7.Theheads may be eccentric or may have other form to produce a longerstroke, as shown in Fig. 8.

My compressing cylinders, arranged as shown, may be aided by one or morecompression cylinders and pistons arranged in the ordinary manner.

I claim as my invention- 1. In an air or gas compressor, the slide 7 andmeans for reciprocating it strongly in a right line in combination witha pair of compressing-pumps arranged on opposite sides thereof andpivotally connected thereto, arranged to oscillate on trunnions near theinner ends so as to give a motion nearly coinciding with that of theslide near each end of the stroke, all substantially as hereinspecified.

' 2. In an air or other fluid compressor, the combination with a pair ofopposed compressin g-cylinders and induction and delivery valvestherefor said cylinders being arranged to oscillate on trunnions, attheir inner ends, of a rolling connection with the inner ends of therods of the compressing-pistons so as to turn without friction on eachother, substantially as specilied.

3. Inan air or other compressor, the combination with a pair of opposedcompressingcylinders arranged to oscillate on trunnions located attheirinner ends, of piston-rods for said cylinders having heads abuttingagainst and arranged to roll on each other, and means for reciprocatingsuch heads and consequently the compressing-pistons, substantially asherein specified.

4. In an air or other compressor, the combination with asupporting-frame, a pair of oscillating compressing-cylinders havingdiametrically-located trunnions each containing an opening 11 for thepassage of the iiuid, a packed recess 12 surrounding such opening andseparated therefrom by a substantial rim 12a, of a plate 13 for eachtrunnion bolted to IOO IIO

the supporting-frame and having an annular with the induction of anotherpair by stuffingboxes maintaining tight joints and allowing the motions,said cylinders moving in unison so that the primary pair simultaneouslydelivers to thereservoir, while the secondary pair similarly receivesthe air of compression, all substantially as herein speciied.

G. In an air or other compressor, the coinbination with acoinpressor-cylinder, of its piston and actuating means, said cylinderhaving induction and delivery valve-chambers, located in its head andcontaining their respective valves, the delivery-valve chamber having acap 45, the inner rim of which has :t port 4S establishing communicationbetween the spaces at the rear of the deliveryvalve and the delivery,and adapted to bc closed by the delivery-valve when unseated,

so as to effect the closing motion of the valve by the subsequentexpansion of the air or other gas thus received, substantially as hereinspecified.

In testimony that I claim the invention above set forth I affix mysignature in presence of two Witnesses.

JONAS CRABTREE. lVitnesses:

M. F. BoYLE, J. B. CLAUTICE.

